(a) Field of the Invention
This invention relates to a system for introducing outdoor air only to a room or space and achieve maximum mixing of the outdoor air with the room air without creating objectionable drafts or turbulence.
(b) Description of the Prior Art
The study of the subject of mechanical ventilation systems and indoor air quality has resulted in at least two publications: a European publication entitled "Ventilation For Buildings, Design Criteria For the Indoor Environment", (draft 31 Jan. 1994); and a U.S. publication entitled "ASHRAE Standard 62-1989, Ventilation For Acceptable Indoor Air Quality". Both these publications identify the requirement that the forced air circulation system should ventilate, but should not create turbulence or drafts that are uncomfortable for the occupants.
Forced air circulation systems are used in buildings occupied by humans. Such systems are used for three basic purposes, namely, heating, cooling and ventilating. Ventilation implies supplying outdoor air and removing pollution that is generated in the building by the occupants. The purpose of all this is to provide a comfortable and healthy environment. The effectiveness of a forced air circulation system in maintaining these conditions depends on how thoroughly the circulated air mixes with the space or room air, and the removal of the used air or contaminated air from the room or space.
Since people are sensitive to drafts and air temperature changes, present practice uses grills or diffusers to introduce the supply air to a space or room with the least turbulence and yet with sufficient movement and circulation to create the best mixing. The mixing is crucial, since it is the way the room or space is heated or cooled, and it is the way the contamination generated by the occupants is picked up and diluted so it can be exhausted from the room or space. However, in the use of grills or diffusers, a very small temperature difference is necessary.
Indoor air problems are a major health concern, and a public health problem that has enormous financial significance in all countries that have buildings that are mechanically ventilated by forced air circulation systems. This is due to the ineffective and inadequate performance of grills and diffusers in achieving thorough mixing of the introduced air and the room air.
The techniques presently in use to improve mixing in a space, are to increase the volume of air delivered to a room or space, i.e., the number of air changes per hour. However, to avoid increasing the energy requirements, present practice is to mix outdoor air or fresh air with recirculated air, i.e., used air, but with no means for positively expelling such mixed air outdoors. Nevertheless, it is known that such a process reduces the quality of the supply air by ignoring a basic public health law, namely, that outdoor air should not be mixed with used air, since used air is contaminated air. It is believed that this fact contributes to the cause of what is called the Sick Building Syndrome. Thus, present practice in the air conditioning industry ignores the fact that the respiratory system is also an avenue for infection.
One way to assist in the ventilation of a room in a building has been by the use of ceiling fans. Ceiling fans have been around for more than a century. The slow moving blades stir the air enough to make persons feel comfortable.
Patented systems have been provided in an attempt to assist in the ventilation of a room in a building. Thus, Canadian Patent No. 832,788 patented Jan. 27th, 1970 by A. Erfelling provided a ventilation apparatus with the arrangement of a ventilator adapted to be driven by motor, for the rooms of a building. The patented invention was alleged to have solved the problem of improving the flow and distribution of the air of a ventilation apparatus within the room of the building and to take care that when drawing-in fresh air it is practically ensured that the amount of fresh air drawn in is not contaminated by the outgoing used air. This was alleged to be achieved by ventilation apparatus comprising a used-air draw-in duct arranged vertically in the room and facing downwardly. A used-air pressure duct was connected to the draw-in duct and extended horizontally and outwardly through the wall of the building. A fresh-air duct was arranged above the used-air pressure duct and extended outwardly through the wall of the building. A connection duct connected the pressure duct with the fresh-air duct. A double flap was formed like a two-armed lever and was adapted to be pivoted between two end positions. In one end position the connection duct was closed by one-half of the flap and both the pressure duct the fresh-air duct was fully opened; in the other end position, the connection duct was opened, the fresh-air duct was closed by the flap half and the used-air pressure duct was closed by the other flap half. An axial-blow fan was adapted to be driven by a motor and was arranged in that part of the horizontal used-air pressure duct which was situated approximately within the range of the wall of the building.
Canadian Patent No. 942,572 patented Feb. 26th, 1974 by A.Ahlberg provided an arrangement at ventilation installations in apartment, office and similar rooms with high requirements on air comfort, including the supply of large fresh air quantities without causing appreciable draught and the removal of exhaust air from the room at an outer wall comprising a window. The patented improvement comprised at least two spaces in the wall formed by plane parallel plates. The first of the spaces was located farthest away from the room interior and formed an exhaust air passageway having one end in direct and free connection with the room adjacent the window, and the other end was adjacent the ceiling of the room connected with exhaust means extending through the remaining space of the arrangement. The second space was located closest to the room interior and was connected to a supply of fresh air adjacent to the ceiling of the room. Its lower part was in direct connection with the room interior. The second space had an air diffuser equipped with a damper means between he connections for the introduction of air to the room in a proportion of fresh air from the supply, and co-ejected room air from the connection with the room interior, the proportion being determined by the damper means.
Canadian Patent No. 1,057,562 patented Jul. 3, 1979 by I. C. Whiteley provided a device for circulating air between the floor and ceiling of a room to reduce temperature stratification and to decrease the energy required to maintain the room at a given temperature. The patented improvement was a floor-ceiling air circulating device comprising a base adapted to be supported on the floor of a room. A duct means extended vertically from the base to define a first flow path which extended from a lower inlet at the base and which terminated at an upper outlet adjacent to the ceiling of the room, and a second flow path which extended from a lower outlet at the base and which terminated at an upper inlet adjacent to the ceiling of the room. A fan was housed in the base for drawing air from the floor via the lower inlet and for forcing the air through the first flow path for discharge at the upper outlet adjacent to the ceiling and for drawing air from the ceiling via the upper inlet and the second flow path for discharge adjacent to the floor at the lower outlet. Air drawn from the ceiling was replaced by air drawn from the floor, and air drawn from the floor was replaced by air drawn from the ceiling.
Canadian Patent No. 1,090,190 patented Nov. 25, 1980 by D. B. Rusth provided a device for generating a circulatory flew of air within a room or closed area of a building structure. The patented improvement was an air circulator comprising a duct suspended from its upper end and which discharged an airflow towards the floor area of the room. A fan and motor assembly was provided. A support structure included a base to which the fan and motor assembly was attached. A hanger suspended the support structure from an overhead structure. The support structure additionally included mounts partially enclosed by the base and to which the upper end of the duct was attached, whereby the duct was in axial relationship with the fan of the fan and motor assembly. The base had a lowermost outer portion outwardly offset from the mounts and the upper end of the duct. The base received a fan-induced flow of heated convective air from the area of the room subjacent the roof or ceiling structure for subsequent downward flow into the duct upper end and passage via the duct to be discharged into an area superjacent the floor of the room to heat the latter area.
Canadian Patent No. 1,134,666 patented Nov. 2nd, 1982 by D. B. Rusth et al provided a device for use in enclosed areas for the purpose of circulating ambient air to avoid temperature stratification. The patented improvement was an air circulator comprising a support structure adapted for attachment to a superjacent support. A fan and motor assembly was supported by the support structure with the fan on a motor output shaft. Mounts were provided on the support structure past which a fan-discharged air moved. A perforate body carried by the mounts and having multiple passageways constrained passing of fan-discharged air for the formation of a linear stream of air. A constrictor subjacent to the perforate body served as a nozzle to constrict and accelerate the stream of air to enhance stream range and hence effectiveness.
U.S. Pat. No. 1,296,968 patented Mar. 11, 1919 by A. Klein provided a method and system for supplying air to interiors. The patented improvement provided a method of supplying air for effecting circulation of such air through the zone of occupancy. The method includes withdrawing air from the interior into a suitable conduit. A current of fresh air was combined therewith and the resulting mixture was discharged into the interior. The current of fresh air effected the withdrawal of the air from the interior and induced the circulation thereof through the conduit and into the interior. The air was withdrawn and introduced at different levels so that circulation thereof was effected through the zone of occupancy.
U.S. Pat. No. 1,925,822 patented Sep. 5, 1993 by W. Shurtleff provided a method and apparatus for heating and ventilating. The patented improvement provided a method of heating and ventilating rooms. The method included heating room air under thermostatic control responsive to thermal conditions at or below the breathing line. The discharge of downwardly-directed air current was thermostatically initiated when the temperature above the breathing line rose to a predetermined degree in excess of the controlled temperature at the breathing line. The speed of dissemination of the downwardly-directed currents under the last mentioned thermostatic control was ultimately increased when the temperature at the high level reached a predetermined maximum to break stratification of air in cold weather. It provided for the dissemination from above of cooling air currents in warm weather.
U.S. Pat. No. 2, 126,230 patented Aug. 9, 1938 by E. R. Troxell, Jr. provided distributing means for conditioned air, and a non-overloading distributing head having a high suction pressure and still maintaining free discharge of air all around the periphery of an open fan. The patented improvement provided a supply duct provided with a plurality of openings. A distributing head was provided adjacent to each opening, each head comprising an open centrifugal-type suction fan having substantially-free discharge of air all around its periphery. Air intakes communicated with the duct on one face only of the fan, the other face of the fan being sealed whereby only duct air can pass through the fan when the fan was operating. A motor was operatively connected to drive the fan. Each head included structure for providing an admixture of air from the space served with the discharge of duct air from the fan. Means were so constructed and arranged that change in the discharge of one of the distributing heads by reason of the stoppage of another of the heads and the leakage of space air back through the stopped head, was obviated.
U.S. Pat. No. 2,267,425 patented Dec. 23rd, 1941 by W. Rowe et al provided an air conditioning unit. The patented air conditioning device included a heat exchanger, a casing with inlet land outlet, and a fan to draw air from the inlet through the heat exchanger to the outlet. An air mixing and diffusing device was provided in co-operation with the outlet. Such device includes an outwardly-flaring annular member attached to the outlet of the casing and a second outwardly-flaring annular member spaced by a distance equal to one-third of the diameter of the fan from the first-mentioned member to form an air passage therebetween. The second member was hollow and was open at top and bottom. The top opening was substantially one-third of the diameter of the fan. Air was induced through the second member and out of the top opening, was mixed with the outlet air and was discharged through the passageway.
U.S. Pat. No. 2,275,295 patented Mar. 3rd, 1942 by G. H. Greenway provided an air conditioning unit. The patented air conditioning unit was adapted to be mounted adjacent the ceiling of a room. It included an elongate casing having an air inlet at its upper end. Such inlet extended substantially throughout the longitudinal width thereof. A curved grille covered the inlet. An air outlet extended substantially throughout the width of the casing at its lower end. Air-current impellers were disposed within the casing adjacent the inlet for circulating air downwardly through the casing. A cooling unit was mounted within the casing and had transverse coils and also upright fins mounted on the coils. The fins had their bottom edges inclined in a direction to cause droplets of water to gravitate out of the path of the air currents.
U.S. Pat. No. 2,354,292 patented Jul. 25, 1944 by A. E. Waterman provided a ventilating system for positive air control in buildings. The patented device was provided in combination with a room having a ceiling. An air duct was positioned above the ceiling and extended from the exterior of the building. The air duct had an inclosure to a downwardly-directed outlet positioned in the ceiling and substantially midway up the sides of the building. An electrically-operated cage-type fan was associated with the outlet, the fan having a vertically-arranged axis, with the cage of the fan being positioned to receive air from the outlet and to discharge it circumferentially and horizontally in contact with the ceiling. A roof ventilator was provided having an inlet which was adapted to receive air from the inclosure a distance from the fan. An opening was provided from the inclosure into the air duct and was positioned a distance from the fan and from the inlet of the roof ventilator. A valve was provided having a hinged support at the side of the opening toward the inlet end of the duct. A thermally-controlled device was associated with the valve and was positioned adjacent to the valve and within the inclosure. Such device had means to move the valve and more or less close the duct and the opening, thereby thermally to control the percentage of outside-to-inside air entering the fan when the fan was operating.
U.S. Pat. No. 2,398,627 patented Apr. 16, 1946 by I. R. Disbro et al provided a ceiling fan system. The patented improvement provided a room having a ceiling and a panel beneath the ceiling. The panel had an opening in the central part thereof for the passage of air therethrough. Outer edges of the panel were spaced from the side walls of the room for forming air passages therebetween. An air impeller was disposed intermediate the ceiling and panel and was in registry with the opening in the panel, for causing air to flow intermediate the ceiling and the panel. The panel had trough-like portions that substantially surrounded the central portion of the panel. Those portions were disposed intermediate the periphery of the air impeller and the outer edges of the panel. Germicidal lamps were disposed in the trough-like portions, the lamps being disposed below the upper surface of the panel.
U.S. Pat. No. 3,669,349 patented Jun. 13, 1972 by W. X. Hall, Jr. provided an air flow control system. The patented system included a powered mixing box adapted to be mounted adjacent to the supply opening for directing air through the supply opening into the room. The powered mixing box had a first inlet opening, a second inlet opening, and an outlet opening. A first structure formed a warm air supply path leading to the first inlet opening of the powered mixing box. A second structure formed a cool air supply path leading to the second inlet opening of the powered mixing box. A first pair of plates were provided, at least one of which was perforated. The first pair of plates was mounted so they were always immediately adjacent the first inlet opening and were transversely disposed in, and substantially normal to the warm air supply path. A second pair of plates was provided, at least one of which was perforated. The second pair of plates were mounted so they were always immediately adjacent the second inlet opening and were transversely disposed in, and substantially normal to the cool air supply path. Means interconnected one plate of each pair for moving one plate of the first pair relative to the other in a first sense, while moving one plate of the second pair relative to the other in a second sense to increase the proportion of air supplied to the powered mixing box through one air supply path while concurrently decreasing the proportion of air supplied to the powered mixing box through the other air supply path. The outlet opening was located in one wall of the powered mixing box and both of the inlet openings were displaced short distances from one wall of the powered mixing box to define a space which was wholly within the powered mixing box and which was bounded by the outlet opening and by the pairs of perforated plates. A fan was mounted in the space within the powered mixing box and was immediately adjacent to the pairs of plates. The fan was disposed within the space within the powered mixing box but was located downstream from the plates of the first pair of plates and also was located downstream from the plate of the second pair of plates. The fan received warm air from the warm air supply path via the first inlet opening and the first pair of plates, and received cool air from the cool air supply path via the second inlet opening and the second pair of plates. The fan mixed the warm air and the cool air and then moved the mixed air through the outlet opening and into the room through the supply opening.
U.S. Pat. No. 3,974,754 patented Aug. 17th, 1976 by J. W. Powlesland et al provided a controlled fluid flow system. The patented improvement provided an enclosure defining an interior space and separating the interior space from the exterior. A plenum was provided within the enclosure. A conduit communicated the plenum with the exterior, whereby gas from the exterior can be admitted to the plenum. The plenum was perforate to permit a relatively slow-speed flow of gas away from the perforate plenum, the plenum and conduit means being the only passageway by which gas from he exterior could enter the interior, apart from access doors and windows. A jet adjacent to the plenum was positioned so as to be within such slow-speed gas flow. The jet was adapted to propel a relatively high-speed jet of the gas toward an exhaust location within the enclosure, thereby to entrain additional gas from the slow-speed gas flow and to urge it toward the exhaust location. Exhaust means were provided at the exhaust location for exhausting substantially all of the gas arriving at the exhaust location to the exterior.
U.S. Pat. No. 4,535,684 patented Aug. 20, 1985 by G. Perng provided a ventilation system for an enclosed space. The patented system was especially suited for an enclosed occupied space which was defined by hollow walls and a ceiling. The system included a fresh air inlet and fresh air passage provided in the lower side of the walls, the fresh air passage having a plurality of fresh air outlet for supplying fresh air into the space. A plurality of exhaust air inlets was provided in the ceiling of the space. A first exhaust air discharge passage communicated with the exhaust air discharge passage communicated with the first discharge passage and was provided in the wall. A second exhaust air discharge passage communicated with the first discharge passage and also was provided in the wall. An exhaust air outlet was provided at the top of the second exhaust air passage. Means were provided for preventing backdraft at the exhaust air outlet, such means including a roof-shaped member having a first and a second flow regulating arrangement, each of which had a plurality of overlapping slats for opening and closing the air outlet. The first and second flow regulating arrangement was so arranged that when one of them was fully closed, the other was fully opened.